disp: msm: dsi: update DSI command buffer for MSM

This change takes care of swapping the byte order in
the packet header to work with MSM hardware.

Change-Id: I38b92a277aa4677d53e263ce343721b8f2b48497
Signed-off-by: Satya Rama Aditya Pinapala <psraditya30@codeaurora.org>